US 3012811 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Dec. 12., 1961 R. J. sANDRocK GRIPPINGTOOL Filed March 2l, 1960 FIG. 2
k c o r Rm m E. V J md n nv m y a R ATTORNEY United States 3,012,811 GRIPPING TOOL Raymond James Sandrock, Lynchburg, Va., assigner to the United States of America as represented hy the United States Atomic Energy Commission Filed Mar. 21, 1960, Ser. No. 16,616 7 Claims. (Cl. 294-83) This invention relates to a releasable gripping tool and more particularly to a gripping tool which is self grasping and remotely actuatable for dis-engaging a load.
In certain applications of lifting or gripping tools it is not possible or convenient to observe visually the operation of the grasping members. For example, in the assembly or disassembly of the fuel elements in a nuclear reactor the device which is to accomplish the lifting and also the placing and releasing of the fuel elements must generally be capable of being self-actuated for gripping the fuel elements and releasable within the reactor only when the fuel element is deposited in place. This is usually alditiicult problem because, in general, it is not possible to observe closely the vposition of the fuel element and the grasping elements within the reactor.
Furthermore, a lifting device for use in a nuclear reactor must be incapable or releasing its load except when proper to do so. An additional and important requirementv of such a device is that its contact with 'the grasping knob of the fuel element must be relatively gentle and activated on slight'contact to avoid excessive jarring of the fuel element. Thus, a relatively lightweight device would be very desirable. Furthermore, since the device becomes radioactive, it should require a minimum of maintenance and hence should be simple in construction.
Devices found in the prior art for accomplishing these functions do notcombine all of the features hereinabove enumerated. For example, a device which will not accidently release its loadl while supporting it may be found to require some minimum visual observation to select the roper moment for releasing the load. Another device which perhaps does not require such visual observation for its operation or actuation may require the use of massive elements to insure actuation in a positive manner.
The present invention combines to a greater extent than heretofore found to be possible, the desirable features described above and in addition, it is a device of great simplicity and utmost reliability. The unit itself is relativelylightweight and is provided with an actuating piston which is spring urged in one direction to accomplish the initial grasping of the lifting knob attached to the object to be lifted.v 'For releasing the object, a solenoid is provided to elfect the releasing movements. To insure that the device will not be actuated to release or grasp a load permaturely, the actuating piston or plunger is maintained positively locked in either of these positions. For this purpose `a slidable sleeve is provided'to insure that the device will function in exactly the manner intended.
Itis-thus a rst object of this invention to provide a remotely actuated pick-updevice for lifting or releasing a load.`
' It is a further object of this invention to provide a self-' actuating pick-up device for grasping a load when the device is in the proper position. Anotherobjectgof this invention is to provide a solenoid actuated releasing device which will not release a load' supported thereby unless the load is placed in a positionv where it would beproperly supported after release of the device.`
i A further object of this invention is load lifting apparatus incapable of releasing said load as long as said liftingdevice provides support for said load.
fj -Still another object of this invention is arelatively corre;l
pact device of simple construction for handling a load with relatively gentleness to avoid causing damage to said load.
Further objects and benefits of this invention will hereinafter become more evident and better understood with the following description making reference to the attached drawing in which:
FIG. l is a sectional elevation View of a preferred embodiment of this device in the condition of about to actuate a load;
FIG. 2 is a View similar to FIG. l except that the lifting device is in a condition of carrying a load; and
FIG. 3 is a partial side view of the device as shown in FIG. 1.
Referring to FIG. 1 there is shown a pick-up tool 1t) supported by a cable 13 to grasp a knob 11 and constructed according to the principles of this invention. Tool 10 consists of a frame 12, a sleeve unit 1d which is slidable with respect to frame 12, as will be later seen, a plunger 16, and a pair of grasping arms 18a and 18b. Frame 12 consists of a main body or grasping arm block 22, a solenoid housing 24 which may be cylindrical in shape, and a cylindrical tubular neck or section 26 which connects and makes integral block 22 with housing 24. Housing 2,4 and neck 26 are thus extensions of main body 22. As best shown in FIG. 3, block 22 is formed of solid material and is provided with a vertical slot 28 in which is fitted the grasping arms 18a and 1817 which are pivoted about shafts 32 and 34 respectively. Arms 18a and 1-8b are provided with rollers 36, 38 and rollers 42, 44 respectively. Rollers 36, 38, 42 and 44 roll on plunger 16 as will be more particularly described below. A stationary guide member 46 of flat construction as illustrated in FIGS. 1 and 3 bridges the opening of slot 2S and extends below the bottom of block 22 to make contact with lifting knob as will be later more particularly seen.
The slidable outer sleeve 14 consists of a major cylindrical portion 52 and a cylindrical extension 54 of smaller diameter riding over the outside of neck or section 26. Cylindrical section 26 is provided with a pair of openings 56 and 58 to accommodate a pair of spherical lock balls 62 and 64 as illustrated. It will be seen that adjacent and above openings 56 and A58 on neck 26 is an annular can move up and down in this narrow range between these two limits.
vPlunger or piston 16 is slidable within frame 12 and extends from within housing 24 down to the plunger guide 46 previously described. Plunger 16 is cylindrical in section and isprovided with a shoulder 74 due to a change of diameter at this point, as shown. A pair of semicircular slots 76 and 78 are located along the outer circumference of plunger -16 immediately below shoulder 74 in the positions illustrated. Slots 76 and 78 are of shape and diameter -toaccommodate lock balls 62 and `64 for a purpose to be later more particularly described.` Adjacent the lower portion of plunger 16 there is a necked down portion 82 havingV an appropriate shape to accomplish the camming action vas will be more particu-l larly described below. The camming action is brought to bear through rollers 36, 38, '42 and 44 on grasping arms 18a and 18h whichare pivoted about shafts 32 andv34 respectively to accommodate the grasping or the releasing y action as is required. For guiding plunger l16, the latter 3 is provided with a slot 84 which accommodates plunger guide 46 as shown.
Turning to the interior of housing 24 on main body il. it will be seen that the former is provided with a lip 86 which is circumferential in nature and extends almost to the surface of plunger 16, forming an annular shoulder. Thus there is enclosed an annular space 87 within section 26 and outside of the outer surface of plunger 16 between the wall formed by lip 86 and the shoulder 74 of plunger 16 at this point. In this space there is provided a spring 8S which Ibiases plunger 16 downwardly.
Adjacent the upper end of plunger 16 is mounted a solenoid unit 92 into which plunger 16 terminates. Unit 92 is supported within housing 24 in any convenient, wellknown fashion. An electrical, iiexible cable 93 connects solenoid 92 to a point outside of tool 10. When solenoid 92 is energized, plunger 16 is urged upwardly overcoming the opposition of spring 88, withdrawing plunger 16 into its position illustrated in FIG. l. When solenoid unit 92 is deenergized spring 88 inuences plunger 16 and moves it down into its lowermost position as illustrated in FIG. 2, except as is otherwise affected by the locking action of balls 62 Aand 64 which now will be more particularly described. A pair of micro-switches 94 and 96 mounted on solenoid 92 are actuated by the movement of plunger 16 into one of its extreme positions, respectively.
lt should be noted at this point that the movement of plunger 16 downwardly cams rollers 36, 38, 42 and 44 so that grasping arms 18a and 18h are pivoted inwardly about their shafts 32 and 34 to come together at their lower tips and enclose lifting knob as shown in FIG. 2. Movement of plunger 16 upwardly causes the separation of arms 18a and 18h and the release of the lifting knob as shown in FIG. 1. It will be noted from FIG. 1 that balls 62 and 64 are shown as resting along the inner surface of slot 78. However, since movable outer sleeve 14 is resting on the top surface of block 22, there is no support behind balls 62 and 64, and they are free to move outwardly into the space between shoulders 72 and 66. Thus should plunger 16 be urged downwardly, it would be free to push aside lock balls 62 and 64 and move downwardly in response to such an urging. However, it will be seen that if movable outer sleeve 14 were raised so that the shoulders 66 and 72 of section 26 and sleeve 54 should come together -balls 62 and 64 will be locked into their slot and grasping arms 18a and 18b will be effectively locked into their position.
The operation of the device shown in FIGS. 1, 2, and 3 is as follows: Assume that lifting unit 10 is supported by cable 13 and is in the position shown in FIG. l ex cept that it has not yet been lowered over lifting knob 11 and thus plunger guide 46 is not resting on knob 11. This means that support of block 22 is from lifting cable 13 through housing 14, through shoulder 66 resting on shoulder 72, and through frame 12 and block 22. Thus balls 62 -and 64 would effectively be locked into their position in annular slot 78 as shown. As unit 10 is lowered so that plunger guide 46 comes in contact with the top of lifting knob 11 the weight of frame 12 will be taken off lifting cable 13 and movable outer sleeve 14 cornes down to rest on block 22 which in turn cornes to rest on lifting knob 11. The movement of sleeve 14 separates the shoulders 72 and 66 thereby releasing the locking action on balls 62 and 64 as illustrated in FIG. 1. At this point, spring 88 urges plunger 16 down provided solenoid 92 is un-energized and causes the separation of balls 62 and 64 into the space provided between abutment 72 and 66. Plunger 16 moves down with its slot 84 engaging with guide 46 as shown in FIG. 2. Grasping arms 18a and 18b are cammed together and lock balls 62 and 64 become opposite slot 76. When lifting cable 13 is again raised, sleeve extension 54 below shoulder 72 locks balls 62 land 64 in place and shoulders i 72 and 66 engage so that lifting knob 11 is lifted and supported in the manner earlier described. In order to lower the load attached to knob 11 and dis-engage it device 1G is lowered until the load is resting on a support (not shown) and the movable outer sleeve 14 is moved slightly downwardly in sliding relationship with respect to frame 12 so that the locking behind balls 62 and 64 in slot 78 is released. At this point, solenoid coil 92 is actuated so that plunger 16 is moved upwardly forcing balls 62 and 64 out of slot 78. This, of course, causes grasping arms 18a and 18b to separate due to the camming action in the lower portion of plunger 16; then the lifting of moveable outer sleeve 14 by cable 13 upwardly locks the balls into the lower spherical groove 78 with arms 13a and 13b open as in FIG. l so that unit 10 is now ree of the load connected to lifting knob 11 and may be `removed free of the load.
Micro-switches 94 and 96 are actuated by plunger 16 in the full up or full down position, respectively. The switches 94 and 96 may be connected through cable 93 to appropriate safety devices such as an air valve in an air line that supplies air to the air hoist that raises gripping unit 10. This interlocking feature prevents move ment of tool 10.
It is thus seen that there has been provided a unique and simplified device for the remote handling of loads in places where visual observation is not appropriate or possible. It is also seen that this device prevents accidental unloading or releasing of the load because of the blocking action which depends only upon the support of the load. Furthermore, it is seen that the device is positive acting in both directions in the sense that one mode of energizing is brought about by the operation of a spring and in the opposite direction by the operation of a solenoid. It will be seen also that the device does not depend for operation on fine tolerances since the grasping arms 18u and 18b may be designed to move over as extensive a distance as is possible within the space limitations permitted.
Of course, it is understood that only one preferred embodiment of this invention has been described and that various other modifications or changes may obviously be resorted to by those skilled in the art without departing from the spirit and scope of this invention as hereinafter defined by the appended claims.
l. A grasping device comprising a main body, a pair of cooperating grasping members pivotally mounted on said main body, cam means slidable in said main body between first and second positions actuating said members in and out of grasping positions, respectively, means normally biasing said cam means into its first position, selectively operable power means upon energization for overcoming said bias means and urging said cam means into its second position, means including a slidable sleeve on a portion of said main body for supporting and lifting said main body, and means responsive to the position of said sleeve for maintaining said cam means locked into its then existing position when said lifting means is supporting said device, thereby locking said grasping members in either of their aforesaid grasping positions.
2. The grasping device of claim 1 in which interlock means is provided to prevent movement of said sleeve when said cam means is in a position intermediate of its first and second positions.
3. The device of claim l in which said bias means is a spring and said power means is a solenoid.
4. Grasping and lifting apparatus comprising a main body, a pair of cooperating grasping members mounted pivotally on said body, a sleeve mounted on said body and slidable with respect thereto within a restricted distance along a vertical axis, means for lifting said apparatus attached to said sleeve, said sleeve being in its lowermost position when said lifting means is slack, slidable cam means extending through said main body and sleeve for Wal "l engaging said grasping members and movable between first and second extreme positions actuating said grasping members in and out of grasping positions, respectively, and means responsive to the raising of said sleeve by said lifting means for locking said cam means in its existing extreme position, said cam means being adjustable between its extreme positions with said sleeve in its lowermost position.
5. The apparatus of claim 4 wherein means are provided to bias said cam means toward its rst extreme posi- :tion and selectively operable power means are provided to overcome said bias means and move said cam means into its second position.
6. The apparatus of claim 4 wherein said locking means consists of slots in said cam means, lock balls in said main body to engage with said slots, and a shoulder in said sleeve to backstop and thereby lock said balls in the adjacent slots in said means when said sleeve is raised by said lifting means, thereby preventing further movement of said cam means.
7. The apparatus of claim 4 in which there s provided a guide member for said cam means to come in contact with a load to be grasped and ylifted as said apparatus is lowered and slacken said lifting means thereby to cause the lowering of said sleeve and the unlocking of said cam means.
References Cited in the le of this patent UNITED STATES PATENTS 2,768,019 Brooks Oct. 23, 1956 2,911,251 Osborn Nov. 3, 1959 2,928,693 Cannon Mar. 15, 1960 2,942,911 Stott June 28, 1960